Situations exist where one unit must be sure of the identity of another unit with which it communicates. Security services, police forces, military organisations and commercial organisations all require to know that an interloper is not attempting access or communications. It is known to use passwords and access codes. However, should knowledge of the passwords or access codes be acquired by a non-authorised individual, there is nothing to stop the non-authorised individual gaining access to sensitive or expensive information or facilities without knowledge of the owner. The present invention seeks to improve over password and access code systems by giving the actual equipment used its own identity which cannot be covered by a fixed access code or password.
Access codes and passwords are fixed. If not fixed, they are generated, and, being generated, have a systematic predictability. The present invention seeks to provide equipment identification means which is truly random and unpredictable.
Units, communicating data to each other, have employed encryption (using an encryption key) to defeat eavesdroppers. Like access codes, encryption keys tend to be fixed, or generated according to a predictable pattern. The present invention seeks to provide encryption keys which are truly unpredictable.